(1) Field of the Invention
This invention relates to a light source module of a projector, and more particularly relates to a light source module capable of preventing fragments from shooting outward when the light bulb is broken.
(2) Description of the Prior Art
FIG. 1 is the schematic view of a typical projecting device. As shown in FIG. 1, the projecting device has a light source module 100, an image module 110, and a projecting module 300. The image module 110 transforms the input image signal into the imaging beams. The imaging beams are projected on a screen through the projecting module 300. The light source module 100 has a light bulb 120 providing light for generating the imaging beams.
The light bulb 120 of the light source module 100 should be bright enough to show the images clearly on the screen (not shown). However, the light bulb 120 generates great heat during lightening. If the heat may not be removed effectively, the life of the light bulb 120 will be shortened. Thus, as shown in FIG. 1, to remove the heat generated by the light bulb 120, the light source module 100 has a fan 160 and an air tunnel 140 in addition. The fan 160 is located by the light bulb 120, while the light bulb 120 is located at the air inlet 140a of the air tunnel 140. The air flow generated by the fan 160 may carry the heat generated by the light bulb 120 outside through the air tunnel 140.
However, during the lighting, the light bulb 120 may be broken because of the internal stress caused by temperature variation or external impact. When the light bulb 120 is broken, as the arrow in FIG. 1A shows, the fragments may be shot directly into the air tunnel 140, or hit the high-speed rotating fan 160 and then be shot into the air tunnel 140. These hot fragments shot into the air tunnel 140 hit the arc angle 140b of the air tunnel 140 and bounded outside, which may hurt human and damage the objects.
As FIG. 2 shows, to solve this problem, a typical way is to dispose a bulb cover 170 over the light bulb 120 to block the fragments. For heat dissipation demand, the bulb cover 170 needs to have openings formed thereon for the fan 160 to bring away the heat generated by the light bulb 120. Thus, the bulb cover 170 may not block all the fragments generated.
Moreover, as shown in FIG. 3, another way is to set a grey-color thermal-resistant foaming rubber layer 180 inside the air tunnel 140. The foaming rubber layer 180 is capable of absorbing the momentum of the fragments for preventing the fragments rebounded and leaving the air tunnel 140. However, the usage of the foaming rubber layer 180 not only increases the cost, its grey-color surface may turn into a glary light-reflecting surface under strong light from the light bulb 120, which may result in light leakage.
Thus, how to provide a safe light source module to avoid the damage to human and environmental objects by the explosion of the light bulb is an urgent problem for the projecting device industry.